1. Field of the Invention
The present invention relates to an apparatus for and a method of processing low-speed circuit data and high-speed packet data, and more particularly, to an apparatus and a method capable of processing low-speed circuit data lower than 64 kbps and high-speed packet data higher than 64 kbps in which a high-speed data network is constructed by converting an LCIN (local CDMA (code division multiple access) interconnection network) for supplying a communication path of packet data among sub-systems in a BSC (base station controller) of CDMA system to an ATM (asynchronous transfer mode) for processing high-speed data, installing a TSB (transcoder selector bank) or an SDU (selector distribution unit) for processing high-speed packet data higher than 64 kbps in the BSC, and linking an ATM switch to an MSC (mobile switching center) to provide a high-speed data service with respect to other network.
2. Description of the Related Art
FIG. 1 is a block diagram illustrating an apparatus for processing voice data and low-speed packet data in a conventional IS-95A system.
As shown in FIG. 1, an apparatus for processing voice data and low-speed packet data in a conventional IS-95A system includes BIN (BTS interconnection network) 50-1a to 50-na for providing a communication path among each block in each BTS (base station transceiver subsystem) 50-1 to 50-n, an LCIN 21 connected to the BIN 50-1a to 50-na so as to provide a communication path among each block in BSC 20-1 to 20-n, a TSB (Transcoder Selector Bank) 22 connected to the LCIN 21 so as to process voice data and circuit data lower than 64 kbps, a CKD (clock distributor) 23 connected to the LCIN 21 and TSB 22 so as to convert a clock received from BSC-GPS and distributes synchronous signals to each block in the BSCs 20-1 to 20-n, an ACP 24 for collecting alarm state of each block in BSCs 20-1 to 20-n, a CCP (call control processor) 25 connected to the LCIN 21 so as to perform a call handling control function of BSCs 20-1 to 20-n, a GCIN (global CDMA interconnection network) 30 connected to the LCIN 21 so as to provide a communication path among BSCs 20-1 to 20-n, a BSM 40 connected to the GCIN 30 so as to perform such functions as BSC and BTS operation, source management, state management, user interface and maintenance and the like, an MSC/VLR 11 connected to the TSB 22 so as to function as a switch for voice data and other data, and an IWF 12 connected to the MSC/VLR 11 so as to process packet data.
Thus-configured apparatus for processing low-speed data in a conventional IS-95A system operates as follows.
When a mobile station (MS) provides one of BTSs 50-1 to 50-n with voice data or low-speed circuit data lower than 64 kbps, one of BINs 50-1a to 50-na in BTSs 50-1 to 50-n provides the LCIN 21 in BSCs 20-1 to 20-n with so-provided voice or low-speed circuit data. The LCIN 21 again provides the TSB 22 with the voice or low-speed circuit data.
The TSB 22 performs 8 k/13 kbps QCELP modulation onto thus-provided voice data, and provides the MSC 10 with the result. Alternately, the TSB 22 aligns the low-speed circuit data to 64 kbps and provides the MSC 10 with thus-aligned low-speed circuit data. The MSC 10 transmits thus-provided voice data or low-speed data of 64 kbps to a PSTN (public switched telephone network).
In the meantime, if the MS provides one of BTSs 50-1 to 50-n with low-speed packet data lower than 64 kbps, thus-provided low-speed packet data is provided again sequentially to the BIN 50-1a to 50-na, LCIN 21, TSB 22, and MSC 10. Thus-provided low-speed packet data is processed by the IWF 12, and the MSC 10 transmits the result to a PSDN (packet switched data network) or Internet.
The apparatus for processing low-speed data in a conventional IS-95A system has disadvantages.
First, a conventional TSB performs 8 k/13 k QCELP modulation onto PCM voice data of 64 kbps and transmits the result to an LCIN. Alternatively, the TSB receives only the traffic data lower than 64 kbps and bypasses the same to the LCIN. Therefore, such an operation causes no problem in IS-95A (DCS/PCS) system which supports service for data of 9.6 kbps. However, a problems arises when it comes to IS-200 system supporting service for data up to 2 mbps, as shown in the following Table 1.
TABLE 1SystemIS-95AIS-95BIS-2000(1×)1S-2000(3×)Data rate9.6 kbps˜64/115 kbps˜307.2 kbps˜2 mbpsFrequency1.25 MHz1.25 MHz1.25 MHz1.25/5 MHZ
Second, routing capacity of the conventional GCIN and LCIN is 187 mbps, respectively, which is appropriate for supporting IS-95A system but is not sufficient for supporting IS-2000 system. When IS-2000 system is operated by such insufficient GCIN and LCIN routing capacity, a bottleneck may occur, thus causing problems in processing voice data which requires a real-time service.
This can be described in more detail as follows.
To calculate GCIN routing capacity and LCIN routing capacity, a single GCIN is connected to 12 BSCs, and a single LCIN has a channel where 960 voice-coder channels and 96 H.S. data channels are combined. In addition, a fixed traffic packet data made up of 22-byte voice data, low-speed data and 756-byte high-speed data is applied. A common handoff rate of 40%, and an inter-BSC soft handoff rate of 40% are applied. As a control packet, 5% of the traffic packet is applied, and the soft handoff rate of high-speed data channel is applied.
Those reference values are applied to the following Equations (1) and (2), and GCIN capacity and LCIN routing capacity are calculated, as shown in the following Table 2.GCIN routing capacity={number of BSCs*number of voice-coder channels*soft handoff rate*inter-BSC soft handoff rate*(traffic transmission rate+control transmission rate)}+{number of BSCs*number of high-speed data channels*soft handoff rate*inter-BSC soft handoff rate*(high-speed data transmission rate+control transmission rate)}  <Equation 1>LCIN routing capacity={number of voice-coder channels*(1+handoff rate)*(traffic transmission rate+control transmission rate)}+{number of high-speed data channels*(1+handoff rate)*(high-speed data transmission rate+control transmission rate)}  <Equation 2>
TABLE 2Routing capacityGCINLCINIS-95A89.51 mbps65.26 mbpsIS-2000(1×)364.1 mbps265.5 mbps
A third disadvantage of the conventional low-speed data processing apparatus in IS-95A system is that soft handoff with BSC of other manufacturer may not be performed due to an IPC communication, i.e., modified HDLC format packet communication protocol, performed in the conventional IS-95A system.
Fourth, in the conventional IS-95A system, a connection between internal blocks is by mode U-LINK (10M, 5M, 2.5M, 1.25M), a communication system is HDLC, and a connection to MSC or BTS supports E1/T1. (2.048M/1.544M). In addition, GCIN provides 104 U-LINK ports in maximum, and LCIN provides 96 U-LINK ports and 112 E1/T1 ports in maximum.
Such a number of interface ports or port speed is sufficient to support IS-95A system, however, a port speed and number of ports for transmitting high-speed data are required in IS-2000 where a routing capacity and transmission rate per channel increase.